1. Field of the Invention
The present invention relates to improved stable aqueous suspensions of precipitated silica and to the use of such suspensions in the papermaking industry.
2. Description of the Prior Art
Aqueous suspensions or slurries of silicas are used in a number of different fields, in particular in the paper-making industry, for coating paper.
Such suspensions have a tendency to undergo sedimentation or gelling, which makes it difficult for them to be transported or stored. Indeed, in very many cases, following transportation of the suspension, or after storage thereof over a time period of greater or lesser length, the formation of a gel or the deposit of a hard layer of pigment, above which exists a slurry which is more fluid but which has a low content of dry solids, is observed. Also, it is often impossible to convert the silica back into a state of suspension, or to produce a slurry which is of sufficiently low viscosity as to be pumpable and therefore capable of being used in an industrial setting. Serious need exists in this art for a solution to these particular problems.